Sol-gel coating compositions including corrosion inhibitor-encapsulated layered metal phosphates and related processes

ABSTRACT

A layered tetravalent metal phosphate composition (e.g., a layered zirconium phosphate composition) and a first corrosion inhibitor (e.g., cerium (III), a vanadate, a molybdate, a tungstate, a manganous, a manganate, a permanganate, an aluminate, a phosphonate, a thiazole, a triazole, and/or an imidazole) is dispersed in an aqueous solution and stirred to form a first solution. A precipitate of the first solution is collected and washed to form a first corrosion inhibiting material (CIM), which includes the first corrosion inhibitor intercalated in the layered tetravalent metal phosphate composition. The first CIM is added to a first sol-gel composition to form a first CIM-containing sol-gel composition. The first CIM-containing sol-gel composition is applied on a substrate to form a CIM-containing sol-gel layer, cured by UV radiation, and thermally cured to form a corrosion-resistant coating. One or more additional sol-gel composition may be applied on the substrate.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation, and claims the benefit, of U.S.patent application Ser. No. 15/431,506, presently pending and filed onFeb. 13, 2017, which claims the benefit of and priority to U.S.Provisional Application No. 62/444,203, filed on Jan. 9, 2017, whereinboth applications are hereby incorporated by reference in theirentireties.

BACKGROUND 1. Technical Field

The present disclosure relates to coating compositions and processesand, more particularly, to sol-gel coating compositions includingcorrosion inhibitor-encapsulated layered metal phosphates and relatedprocesses.

2. Related Art

High strength alloys such as aluminum alloys are widely used in variousindustries such as the aerospace industry due to their high strength toweight ratio. However these alloys are prone to corrosion due to thepresence of alloying materials.

In order to protect these alloys from the environment, a chromeconversion coating may be provided on a surface of an alloy followed byapplication of primer and a top coat. Although organic paint systemsapplied on the surface provide good barrier properties againstcorrosion, even small defects formed in the organic paint providepathways for the ingress of electrolyte to the metallic surface, whichinitiates localized corrosion. Therefore, chromium-based conversioncoatings have been used in anti-corrosion pretreatments beforeapplication of organic coatings. However, hexavalent chromium compoundshave harmful effects.

Thus, there is a need for coating compositions and processes that arechromium-free while providing a coating that is corrosion-resistant.

SUMMARY

In accordance with embodiments of the present disclosure, variousmethods and formulations are provided relating to sol-gel coating ofsubstrates (e.g., an aluminum substrate, an aluminum alloy substrate orother substrate). A sol-gel layer formed on a substrate advantageouslyprovides corrosion protection. Further, the sol-gel layer advantageouslyprovides enhanced adhesion between the substrate and a paint system(e.g., primer and paint).

In one aspect, a method includes dispersing a layered tetravalent metalphosphate composition (e.g., a layered zirconium phosphate composition)and a first corrosion inhibitor (CI) (e.g., cerium (III), a vanadate, amolybdate, a tungstate, a manganous, a manganate, a permanganate, analuminate, a phosphonate, a thiazole, a triazole, and/or an imidazole)in an aqueous solution and stirring to form a first solution, collectinga precipitate of the first solution, and washing the precipitate of thefirst solution to form a first corrosion inhibiting material (CIM). Thefirst CIM includes the first corrosion inhibitor intercalated in thelayered tetravalent metal phosphate composition.

In another aspect, the method further includes adding the first CIM to afirst sol-gel composition to form a first CIM-containing sol-gelcomposition. In another aspect, the method further includes applying thefirst CIM-containing sol-gel composition on a substrate to form aCIM-containing sol-gel layer, curing the CIM-containing sol-gel layer byUV radiation, and thermally curing the CIM-containing sol-gel layer toform a corrosion-resistant coating.

In another aspect, the method further includes applying the firstCIM-containing sol-gel composition on a substrate to form a firstCIM-containing sol-gel layer, curing the first CIM-containing sol-gellayer by UV radiation, applying a second CIM-containing sol-gelcomposition on the substrate to form a second CIM-containing sol-gellayer, curing the second CIM-containing sol-gel layer by UV radiation,and thermally curing a plurality of sol-gel layers including the firstCIM-containing sol-gel layer and the second CIM-containing sol-gel layerto form a corrosion-resistant coating. In some examples, the firstCIM-containing sol-gel layer is applied before the second CIM-containingsol-gel layer is applied. In other examples, the first CIM-containingsol-gel composition is applied after the second CIM-containing sol-gelcomposition is applied. The second CIM-containing sol-gel composition isformed, for example, by dispersing a Zn—Al layered double hydroxide(LDH) composition and a second corrosion inhibitor in a solvent andstirring to form a second solution, collecting a precipitate of thesecond solution, washing the precipitate of the second solution to forma second CIM, and adding the second CIM to a second sol-gel compositionto form the second CIM-containing sol-gel composition. The second CIMincludes the second corrosion inhibitor intercalated in the Zn—Al LDHcomposition.

In an aspect, a first CIM includes a layered tetravalent metal phosphatecomposition including nanoparticles of layered tetravalent metalphosphate (e.g., layered zirconium phosphate), and a first corrosioninhibitor (e.g., cerium (III), a vanadate, a molybdate, a tungstate, amanganous, a manganate, a permanganate, an aluminate, a phosphonate, athiazole, a triazole, and/or an imidazole). The first corrosioninhibitor is intercalated in the nanoparticles of layered tetravalentmetal phosphate.

In another aspect, a first sol-gel composition includes the first CIMand a first polymer composite of one or more alkoxysilanes, a zirconiumalkoxide, and an organic acid. In yet another aspect, acorrosion-resistant coated product includes a first CIM-containingsol-gel layer including the first sol-gel composition. The second CIMincludes, for example, a Zn—Al LDH composition including nanoparticlesof Zn—Al LDH and a second corrosion inhibitor intercalated in thenanoparticles of the Zn—Al LDH.

The scope of the invention is defined by the claims, which areincorporated into this section by reference. A better understanding ofthe methods and formulations for sol-gel coating of the presentdisclosure, as well as an appreciation of the above and additionaladvantages thereof, will be afforded to those of skill in the art by aconsideration of the following detailed description of one or moreexample embodiments thereof. In this description, reference is made tothe various views of the appended sheets of drawings, which are brieflydescribed below, and within which, like reference numerals are used toidentify like ones of the elements illustrated therein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example process for preparing a first corrosioninhibiting material in accordance with an embodiment of the presentdisclosure.

FIG. 2 illustrates an example process for preparing a sol-gelcomposition in accordance with an embodiment of the present disclosure.

FIG. 3 illustrates an example process for forming a corrosion-resistantcoating that includes a sol-gel layer with CIM on a substrate inaccordance with an embodiment of the present disclosure.

FIG. 4 illustrates a diagrammatic cross-sectional view of an examplecorrosion-resistant coating on a substrate in accordance with anembodiment of the present disclosure.

FIG. 5 illustrates an example process for preparing a corrosioninhibiting material that includes a corrosion inhibitor-intercalated LDHcomposition in accordance with an embodiment of the present disclosure.

FIG. 6 illustrates an example process for preparing a Zn—Al layereddouble hydroxide (LDH) composition in accordance with an embodiment ofthe present disclosure.

FIG. 7 illustrates an example process for forming a corrosion-resistantcoating that includes one or more sol-gel layers on a substrate inaccordance with an embodiment of the present disclosure.

FIGS. 8A-F illustrate diagrammatic cross-sectional views of examplecorrosion-resistant coatings that include a plurality of sol-gel layersformed on substrates in accordance with embodiments of the presentdisclosure.

FIG. 9 shows an X-ray powder diffraction (XRD) pattern of an α-zirconiumphosphate composition that may be used in the process of FIG. 1 .

FIG. 10A and FIG. 10B show scanning electron microscope (SEM) images ofan α-zirconium phosphate composition that may be used in the process ofFIG. 1 at low magnification and at high magnification, respectively,illustrating the layered sheet like structure of the α-zirconiumphosphate composition.

FIG. 11 shows an XRD pattern of a cerium-intercalated layeredα-zirconium phosphate prepared by the process of FIG. 1 .

FIG. 12 shows an XRD pattern of the vanadate-intercalated layeredα-zirconium phosphate prepared by the process of FIG. 1 .

FIG. 13 is an image of an uncoated substrate after salt spraycorrosion-resistance testing.

FIGS. 14A-B, 15A-B, 16A-B, 17A-B, and 18A-B show coated substratesformed by the process of FIG. 7 after salt spray corrosion-resistancetesting.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

The terms “substituent”, “radical”, “group”, “moiety,” and “fragment”may be used interchangeably.

Singular forms “a” and “an” may include plural reference unless thecontext clearly dictates otherwise.

The number of carbon atoms in a substituent can be indicated by theprefix “CA-B” where A is the minimum and B is the maximum number ofcarbon atoms in the substituent.

The term “alkyl” embraces a linear or branched acyclic alkyl radicalcontaining from 1 to about 15 carbon atoms. In some embodiments, alkylis a C₁₋₁₀ alkyl, C₁₋₆ alkyl, or C₁₋₃ alkyl radical. Examples of alkylinclude, but are not limited to, methyl, ethyl, propyl, isopropyl,butyl, isobutyl, tert-butyl, sec-butyl, pentan-3-yl (i.e.,

and the like.

The term “alkoxy” is RO— where R is alkyl. Non-limiting examples ofalkoxy include methoxy, ethoxy, propoxy, n-butyloxy, and tert-butyloxy.The terms “alkyloxy”, “alkoxy,” and “alkyl-O—” may be usedinterchangeably.

The term “methacryl” is

The term “methacryloxy” is

The term “methacryloxyalkyl” embraces alkyl substituted withmethacryloxy. Non-limiting examples of methacryloxyalkyl includemethacryloxyethyl, methacryloxypropyl, and

The term “glycidyl” is

The term “glycidyloxy” is

The terms “glycidyloxy” and “glycidoxy” may be used interchangeably.

The term “glycidoxyalkyl” embraces alkyl substituted with glycidoxy.Non-limiting examples of glycidoxyalkyl include, glycidoxyethyl, andglycidoxypropyl, and glycidoxybutyl. The terms “glycidyloxyalkyl” and“glycidoxyalkyl” may be used interchangeably.

The term “aminoalkyl” embraces an amino radical attached to a parentmolecular scaffold through an alkyl radical (e.g., NH₂-alkyl-scaffold).

The term “aryl” refers to any monocyclic, bicyclic, or tricycliccyclized carbon radical, wherein at least one ring is aromatic. Anaromatic radical may be fused to a non-aromatic cycloalkyl orheterocyclyl radical. Aryl may be substituted or unsubstituted. Examplesof aryl include phenyl and naphthyl.

The term “aralkyl” embraces aryl attached to a parent molecular scaffoldthrough alkyl and may be used interchangeably with the term “arylalkyl.”Examples of aralkyl include benzyl, diphenylmethyl, triphenylmethyl,phenylethyl, and diphenylethyl. The terms “benzyl” and “phenylmethyl”may be used interchangeably.

The term “silane” is a compound containing silicon.

The term “organosilane” is a silane having at least one silicon tocarbon bond.

The term “alkoxysilane” is a silane having at least one silicon toalkoxy bond.

The term “organoalkoxysilane” is a silane having at least one silicon tocarbon bond and at least one silicon to alkoxy bond.

The term “about,” as used herein when referring to a measurable valuesuch as an amount, concentration, time and the like, is meant toencompass variations of ±20%, ±10%, ±5%, ±1%, ±0.5%, or even ±0.1% ofthe specified value.

Compositions and processes relating to sol-gel coating of substratessuch as metal or metal alloy substrates (e.g., aluminum substrates,aluminum alloy substrates or other substrates) are provided. Sol-gelcoating may be used as a chrome-free pretreatment on substrates prior tothe application of organic coatings such as primer and paint. Thepretreatment may be performed by applying a layer of a sol-gelcomposition that includes a corrosion inhibiting material (CIM). Thesol-gel composition is obtained as a product of hydrolysis andcondensation of a mixture of organosilanes and a metal alkoxide, alongwith a corrosion inhibitor (CI) (e.g., a corrosion inhibiting compoundor a corrosion inhibiting element) encapsulated (e.g., intercalated) innanoparticles (also referred to as nanocarriers or nanocontainers) madeup of layered metal phosphates. Nanoparticles have a size ranging fromabout 1 nm to about 1000 nm (e.g., a size ranging from about 1 nm toabout 200 nm, a size ranging from about 1 nm to about 100 nm, or othersize range). Ultraviolet (UV) radiation is used to densify the sol-gellayer in addition to, or instead of, thermal curing the sol-gel layer.Thermal curing may include exposing the sol-gel layer to a hightemperature (e.g., in a hot air circulated oven). Alternatively, or inaddition, thermal curing may include exposing the sol-gel layer toinfrared (IR) radiation or near IR radiation, which reduces curing time.Advantageously, the sol-gel coating composition may be low temperaturecurable, provide excellent barrier protection, and possess self-healingproperties to provide prolonged corrosion protection. Further, thesol-gel layers formed using the sol-gel coating composition may releasecorrosion inhibitors on demand.

FIG. 1 illustrates an example process 100 for preparing a corrosioninhibiting material. The corrosion inhibiting material includes alayered metal phosphate (e.g., a layered zirconium phosphate)encapsulating one or more corrosion inhibitors. The corrosion inhibitingmaterial may be an organic corrosion inhibiting material that includesone or more organic corrosion inhibitors, an inorganic corrosioninhibiting material that includes one or more organic corrosioninhibitors, or a combination corrosion inhibiting material that includesone or more organic corrosion inhibitors and one or more inorganiccorrosion inhibitors.

At block 102, a layered metal phosphate composition (e.g., a layeredtetravalent metal phosphate composition) is added to a solution. Forexample, the layered tetravalent metal phosphate composition in anamount ranging from about 1 to about 100 g per 1 L of the solution isadded to the solution. The amount of the layered tetravalent metalphosphate may be 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65,70, 75, 80, 85, 90, 95, or 100 g per 1 L of the solution, where anyvalue may form an upper end point or a lower end point, as appropriate.

In an aspect, the layered tetravalent metal phosphate composition is alayered zirconium phosphate composition of Formula I:Zr(HPO₄)₂ ·nH₂O  Formula I

In another aspect, the layered tetravalent metal phosphate compositionis an α-Zirconium phosphate composition of Formula II:Zr(HPO₄)₂·H₂O  Formula IIThe layered α-zirconium phosphate composition may be formed, forexample, by mixing a zirconyl chloride solution and a phosphoric acidsolution to form a mixture, collecting a precipitate of the mixture, andthen washing and drying the precipitate that includes the layeredα-zirconium phosphate composition.

In yet another aspect, the layered tetravalent metal phosphatecomposition is a γ-Zirconium phosphate composition of Formula III:Zr(PO₄)(H₂PO₄)·2H₂O  Formula III

At block 104, a corrosion inhibitor is added to the solution. Thecorrosion inhibitor includes an inorganic corrosion inhibitor, anorganic corrosion inhibitor, or both. For example, the corrosioninhibitor in an amount that is about equimolar to the layeredtetravalent phosphate composition is added to the solution.

In an aspect, the organic corrosion inhibitor is an imidazole, atriazole, a tetrazole, a thiazole, a thiadiazole, a benzimidazole, abenzotriazole, a benzothiazole, a quinoline, phytic acid, a phosphonate,an organophosphonic acid, or an oil. The oil includes saturated and/orunsaturated fatty acids such as stearic acid, palmitic acid, oleic acid,linoleic acid, and/or linolenic acid.

Specific examples of the organic corrosion inhibitor include1-(3-aminopropyl)imidazole, 1H-1,2,3-triazole,4-methyl-4H-1,2,4-triazole-3-thiol, 1,2,4-triazole-3-carboxylic acid,3-amino-1,2,4-triazole-5-thiol, 4H-1,2,4-triazol-4-amine,3-mercapto-4-methyl-4H-1,2,4-triazole,5-phenyl-1H-1,2,4-triazole-3-thiol, 1-methyl-1H-tetrazole-5-thiol,1H-tetrazole-5-acetic acid, 4-methyl-1,3-thiazole-5-carboxylic acid,1,3,4-thiadiazole-2,5-dithiol, 1H-benzimidazole-2-carboxylic acid,1H-benzotriazole (BTA), 2-mercaptobenzothiazole (MBT),8-hydroxyquinoline, phytic acid, iminodimethylphosphonic acid, aminotris(methylenephosphonic acid) (ATMP), ethylenediaminetetra(methylenephosphonic acid) (EDTMP),1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), diethylenetriaminepenta(methylenephosphonic acid) (DTPMP), and vegetable oil (e.g.,linseed oil or other vegetable oil).

In an aspect, the inorganic corrosion inhibitor is a salt of an oxyanionof a transition metal, a post-transition metal, a metalloid, or apolyatomic non-metal. In another aspect, the inorganic corrosioninhibitor includes cerium (III), a vanadate, a molybdate, a tungstate, aphosphate, a manganous, a manganate, a permanganate, or an aluminate.

Specific examples of the inorganic corrosion inhibitor include sodiummetavanadate, potassium permanganate, sodium molybdate, and sodiumtungstate.

At block 106, the solution is stirred. Stirring may be performed for atime period ranging from 2 to about 48 h. The time period may be about2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 28, 32, 36, 40, 44, or 48 h,where any value may form an upper end point or a lower end point, asappropriate. A corrosion inhibitor-encapsulated layered tetravalentmetal phosphate is formed as a result of block 106. The layeredtetravalent metal phosphate composition and the corrosion inhibitor aredispersed in the solution, and the layered tetravalent metal phosphatecomposition is intercalated with the corrosion inhibitor such that thelayered tetravalent metal phosphate composition functions asnanocontainers that encapsulate the corrosion inhibitor.

At block 108, a precipitate of the solution is collected, for example,by centrifugation. The precipitate is washed at block 110 and dried atblock 112 to form the corrosion inhibiting material. For example, theprecipitate is washed one or more times with water until the pH of thesupernatant is neutral, and then dried in a drying oven. The corrosioninhibiting material includes a corrosion inhibitor-containing layeredtetravalent metal phosphate composition (also referred to as a corrosioninhibitor-incorporated layered tetravalent metal phosphate composition,a corrosion inhibitor-intercalated layered tetravalent metal phosphatecomposition, or a corrosion inhibitor-encapsulated layered tetravalentmetal phosphate composition).

If an organic corrosion inhibitor is used in block 104, the corrosioninhibiting material is an organic corrosion inhibiting material thatincludes the organic corrosion inhibitor encapsulated in the layeredtetravalent metal phosphate composition. If an inorganic corrosioninhibitor is used in block 104, the corrosion inhibiting material is anorganic corrosion inhibiting material that includes the organiccorrosion inhibitor encapsulated in the layered tetravalent metalphosphate composition. Accordingly, in embodiments in which both aninorganic corrosion inhibiting material and an organic corrosioninhibiting material are desired, process 100 may be performed twice,once using an organic corrosion inhibitor at block 104 and once using aninorganic corrosion inhibitor at block 104.

In some embodiments, a combination corrosion inhibiting material thatincludes the layered tetravalent metal phosphate compositionencapsulating both an organic corrosion inhibitor and an inorganiccorrosion inhibitor may be formed by mixing an organic corrosioninhibiting material and an inorganic corrosion inhibitor each preparedby respective process 100, or by preparing a solution including bothtypes of corrosion inhibitors at block 104 in one process 100.

Blocks 102-112 may be performed in the order presented or in a differentorder and/or one or more blocks may be omitted in some embodiments. Forexample, block 102 may be performed before, after, or simultaneouslywith block 104. Further, in another embodiment, the compounds of blocks102 and 104 are dispersed in separate solutions and then combined.

FIG. 2 illustrates an example process 200 for preparing a sol-gelcomposition. A low temperature curable matrix sol is synthesized in twoparts (Composition A and Composition B), the two parts are mixedtogether, additional compounds are added and stirred, and a corrosioninhibiting material is added to obtain a sol-gel composition.

At block 202, Composition A is prepared from an alkoxysilane such as anorganoalkoxysilane. An alkoxysilane is contacted with water and aninorganic acid (e.g., HCl, HNO₃, H₃PO₄, or other inorganic acid) to formComposition A.

For example, an alkoxysilane is mixed with water and stirred, and aninorganic acid is added to the solution of the alkoxysilane and waterand stirred in an ice bath until the solution turns transparent. Theratio of the number of moles of the alkoxysilane (which is equal to thenumber of moles of silicon from the alkoxysilane) to the number of molesof water (n_(Si)/n_(water)) in Composition A ranges from about 0.5 toabout 2. The ratio may be, for example, about 0.5, 0.6, 0.7, 0.8, 0.9,1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2.0, where anyvalue may form an upper end point or a lower end point, as appropriate.

In an aspect, an alkoxysilane of Formula IV is used as Precursor A:R_(A)—Si—(R_(B))₃  Formula IVwherein;R_(A) is methacryloxyalkyl or glycidoxyalkyl; andR_(B) is alkoxy.

In another aspect, R_(A) is methacryloxyalkyl (e.g., methacryloxymethyl,methacryloxyethyl, methacryloxypropyl, methacryloxybutyl, or othermethacryloxyalkyl) or glycidoxyalkyl (e.g., glycidoxymethyl,glycidoxyethyl, glycidoxypropyl, glycidoxybutyl); and each R_(B) isindependently alkoxy (e.g., methoxy, ethoxy, propoxy).

Specific examples of R_(A)—Si—(R_(B))₃ include3-methacryloxypropyltrimethoxysilane,3-methacryloxypropyltriethoxysilane,3-glycidyloxypropyltrimethoxysilane, and 3-glycidoxypropylethoxysilane.

In some aspects, an alkoxysilane used as Precursor A of a sol-gelcomposition includes methacryloxyalkyl alkoxysilane (an alkoxysilane ofFormula IV in which R_(A) is methacryloxyalkyl) and/or a glycidoxyalkylalkoxysilane (an alkoxysilane of Formula IV in which the R_(A) isglycidoxyalkyl). The methacryloxyalkyl alkoxysilane and/or theglycidoxyalkyl alkoxysilane are used, for example, to facilitatepolymerization of the sol-gel composition when exposed to UV radiation.

At block 204, Composition B is prepared from a transition metal alkoxidesuch as a zirconium alkoxide. A zirconium alkoxide is contacted with anorganic acid such as a carboxylic acid (e.g., acrylic acid, methacrylicacid (MAA), ethacrylic acid, crotonic acid, itaconic acid, maleic acid,fumeric acid, or other carboxylic acid) to form Composition B.

For example, the zirconium alkoxide is mixed with methacrylic acid andstirred. The ratio of the number of moles of the zirconium alkoxide(which is equal to the number of moles of zirconium from the zirconiumalkoxide) to the ratio of the number of moles of methacrylic acid((n_(Zr)/n_(MAA)) ranges from about 0.5 to about 2. The ratio may be,for example, about 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4,1.5, 1.6, 1.7, 1.8, 1.9, or 2.0, where any value may form an upper endpoint or a lower end point, as appropriate.

In an aspect, a zirconium alkoxide of Formula V is used as Precursor B:Zr—(R_(C))₄  Formula Vwherein;R_(C) is alkoxy.

In another aspect, each R_(C) is independently alkoxy (methoxy, ethoxy,n-propoxy, isopropoxy, n-butoxy, tert-butoxy, or other alkoxy).

Specific examples of Zr—(R_(C))₄ include zirconium ethoxide, zirconiumn-propoxide, zirconium isopropoxide, zirconium n-butoxide, and zirconiumtert-butoxide.

In some aspects, a zirconium alkoxide is used as Precursor B of asol-gel composition, for example, to match the coefficient of thermalexpansion of the sol-gel composition with a substrate. The zirconiumalkoxide may be used in an amount such that the coefficient of thermalexpansion of the sol-gel composition is equal to or about thecoefficient of thermal expansion of the substrate.

At block 206, Composition A and Composition B are mixed together. Forexample, Composition B is added to Composition A under stirring to avoidagglomeration, and the mixture of Composition A and Composition B isstirred in an ice bath and then stirred at room temperature so that thetemperature of the mixture reaches room temperature.

At block 208, one or more alkoxysilanes such as one or moreorganoalkoxysilanes are added to the mixture of Composition A andComposition B. One or more alkoxysilanes and an organic acid such as acarboxylic acid (e.g., acrylic acid, methacrylic acid, ethacrylic acid,crotonic acid, itaconic acid, maleic acid, fumeric acid, or othercarboxylic acid) are contacted with the mixture of Composition A andComposition B to form a sol-gel composition.

For example, each of one or more alkoxysilanes are added to the mixtureand stirred. Then, methacrylic acid is added to the resulting mixtureand stirred. Optionally, an inorganic acid is added before, togetherwith, or after the organic acid.

In an aspect, one or more alkoxysilane of Formula VI is used asPrecursor C:R_(D)—Si—(R_(E))₃  Formula VIwherein;R_(D) is aryl, aralkyl, glycidoxyalkyl, or aminoalkyl; andR_(E) is alkoxy.

In another aspect, R_(D) is aryl (e.g., phenyl or other aryl), aralkyl(e.g., benzyl, phenylethyl, phenylpropyl, or other aralkyl),glycidoxyalkyl (e.g., glycidomethyl, glycidoxyethyl, glycidoxypropyl,glycidoxybutyl, or other glycidoxyalkyl), or aminoalkyl (e.g.,aminomethyl, aminoethyl, aminopropyl, aminobutyl, or other aminoalkyl);and each R_(E) is independently alkoxy (e.g., methoxy, ethoxy, propoxy).

Specific examples of R_(D)—Si—(R_(E))₃ include phenyltrimethoxysilane,phenyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane,3-glycidoxypropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and3-aminopropyltriethoxysilane.

In some aspects, one or more alkoxysilanes used as Precursor C of asol-gel composition include an aryl alkoxysilane (an alkoxysilane ofFormula VI in which R_(D) is aryl), a glycidyloxyalkyl alkoxysilane (analkoxysilane of Formula VI in which R_(D) is glycidoxyalkyl), and/or anaminoalkyl alkoxysilane (an alkoxysilane of Formula VI in which R_(D) isaminoalkyl). The aryl alkoxysilane is used, for example, to improve thebarrier properties of a coating formed from the sol-gel composition. Theglycidyloxyalkyl alkoxysilane is used, for example, to generate a thickcoating. The aminoalkyl alkoxysilane is used, for example, to improvethe adhesion of the sol-gel composition to a substrate when deposited.

In an example, an aryl alkoxysilane is added to the mixture and stirred.Then, an aminoalkyl alkoxysilane is added to the mixture and stirred.Then, a glycidyloxyalkyl alkoxysilane is added to the mixture. Then,methacrylic acid is added and stirred. An inorganic acid may also beadded. The order of the alkoxysilanes that are added may be changed inother examples.

The total amount of the alkoxysilanes, which includes the alkoxysilaneused in block 202 and the one or more alkoxysilanes used in block 208,and the amount of the zirconium alkoxide used in block 204 are such thatthe sol-gel composition has a ratio of a number of moles ofalkoxysilanes (which is equal to the number of moles of silicon from thealkoxysilanes) to a number of moles of zirconium alkoxide (which isequal to the number of moles of zirconium from the zirconium alkoxide)(n_(Si)/n_(Zr)) ranging from about 2 to about 10. The ratio of thenumber of moles of silicon to the number of moles of zirconium(n_(Si)/n_(Zr)) may be about 2, 3, 4, 5, 6, 7, 8, 9, or 10, where anyvalue may form an upper end point or a lower end point, as appropriate.

In some examples, one or more of the stirring performed in blocks 202,204, 206, and/or 208 may be performed for a time period ranging fromabout 10 min to about 120 min. The stirring performed in blocks 202,204, 206, and/or 208, may be performed for a time period of about 10,20, 30, 40, 50, 60, 70, 80, 90, 100, 110, or 120 min, where any valuemay form an upper end point or a lower end point, as appropriate.

At block 210, the sol-gel composition is diluted with a solvent such asalcohol (e.g., isopropanol or other solvent) and stirred. The dilutionof the sol-gel composition, the stirring to age the sol-gel composition,or both (e.g., block 210 entirely) may be omitted in some embodiments.

For example, the sol-gel composition is diluted with isopropanol in aweight ratio of about 1:1. The diluted sol-gel composition, or thesol-gel composition formed by block 308 if dilution is omitted, isstirred to age the sol-gel composition for a time period ranging from 1to about 24 hours (h). The stirring to age the sol-gel composition maybe performed for a time period of about 1, 2, 3, 4, 5, 6, 9, 12, 15, 18,21, or 24 h, where any value may form an upper end point or a lower endpoint, as appropriate.

At block 212, a photoinitiator is added to the sol-gel compositionformed by block 210 (or by block 208 for embodiments in which block 210is omitted) and stirred.

For example, a photoinitiator in an amount ranging from about 0.5 toabout 3 parts by weight per 100 parts by weight of the sol-gelcomposition (the weight of the sol-gel with the photoinitiator to beadded or, alternatively, the weight of the sol-gel before adding thephotoinitiator) is added, and the sol-gel composition with thephotoinitiator is stirred. The amount of the photoinitiator may be about0.5, 1, 1.5, 2, 2.5, or 3 parts by weight per 100 parts of the sol-gelcomposition, where any value may form an upper end point or a lower endpoint, as appropriate. The stirring may be performed for a time periodranging from about 10 to about 60 min. The stirring may be performed fora time period of about 10, 20, 30, 40, 50, or 60 min, where any valuemay form an upper end point or a lower end point, as appropriate. Oncethe photoinitiator is added, exposure of the sol-gel composition tolight may be avoided by covering a container for the sol-gel composition(e.g., using aluminum foil) and/or storing in an amber-coloredcontainer.

At block 214, a corrosion inhibiting material is added to the sol-gelcomposition to form a CIM-containing sol-gel composition.

For example, a corrosion inhibiting material prepared by process 100 ofFIG. 1 in an amount ranging from about 0.5 to about 10 parts by weightper 100 parts by weight of the sol-gel composition (the weight of thesol-gel with the corrosion inhibiting material to be added or,alternatively, the weight of the sol-gel before adding the corrosioninhibiting material) is added to the sol-gel composition and stirred toform a CIM-containing sol-gel composition. The amount of the corrosioninhibiting material may be about 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8,9, or 10 parts by weight per 100 parts by weight of the sol-gelcomposition, where any value may form an upper end point or a lower endpoint, as appropriate.

In another example, a corrosion inhibiting material in an amount of thesol-gel composition is an amount ranging from about 1 to about 10 partsby weight per 100 parts by weight of the solid content of the sol-gelcomposition is added to the sol-gel composition and stirred to form aCIM-containing sol-gel composition. The amount of the corrosioninhibiting material may be about 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 partsby weight per 100 parts by weight of the solid content of the sol-gelcomposition, where any value may form an upper end point or a lower endpoint, as appropriate. The sol-gel composition may have a solid contentranging from about 10 to about 70 parts by weight per 100 parts byweight of the sol-gel composition. The sol-gel composition may have asolid content of about 10, 20, 30, 40, 50, 60, or 70 parts by weight per100 parts by weight of the sol-gel composition, where any value may forman upper end point or a lower end point, as appropriate.

In embodiments in which a plurality of sol-gel compositions are used(e.g., a sol-gel composition not containing a corrosion inhibitingmaterial and/or one or more sol-gel compositions each containing adifferent corrosion inhibiting material), process 200 may be performed aplurality of times to form each sol-gel composition. Alternatively, thesol-gel composition may be divided into two or more batches and block214 may be performed for each desired CIM-containing sol-gelcompositions using a respective corrosion inhibiting material.

Blocks 202-214 of process 200 may be performed in the order presented orin a different order and/or one or more blocks may be omitted in someembodiments. For example, blocks 210, 212, and 214 may be performed in adifferent order. Further, to form a sol-gel composition without acorrosion inhibiting material, block 214 is omitted.

FIG. 3 illustrates an example process 300 for forming acorrosion-resistant coating that includes a sol-gel layer (e.g., asol-gel coating) on a substrate such as a panel (e.g., an aluminumsubstrate, an aluminum alloy substrate, or other substrate). A sol-gelcomposition is applied to a substrate, and the sol-gel composition iscured by UV light and/or thermally cured.

At block 302, a CIM-containing sol-gel composition prepared by process200 of FIG. 2 is applied to a substrate. For example, the CIM-containingsol-gel composition is contacted with the substrate to form aCIM-containing sol-gel layer such as by dipping the substrate in theCIM-containing sol-gel composition, by immersing the substrate in theCIM-containing sol-gel composition, by spraying the CIM-containingsol-gel composition on the substrate, and/or by other methods ofapplying the CIM-containing sol-gel composition to the substrate. If dipcoating is used, the CIM-containing sol-gel layer can be deposited usinga withdrawals speed ranging from about 1 to about 15 mm/s (e.g., about 5to about 12 mm/s, about 10 mm/s, or other withdrawal speed). Thewithdrawal speed may be about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,14, or 15 mm/s, where any value may form an upper end point or a lowerend point, as appropriate.

At block 304, the CIM-containing sol-gel layer formed by block 302 iscured by UV radiation. For example, the UV radiation has a light doseranging from about 500 to about 1000 mJ/cm². The UV radiation may have alight dose of about 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, or1000 mJ/cm², where any value may form an upper end point or a lower endpoint, as appropriate. The curing by UV radiation may be performed for atime period ranging from about 0.5 to about 30 min. The time period maybe about 0.5, 1, 2, 3, 4, 5, 10, 15, 20, 25, or 30 min, where any valuemay form an upper end point or a lower end point, as appropriate.

At block 306, the sol-gel layer is thermally cured. For example, thesol-gel layer is thermally cured at a temperature ranging from about 70to about 90° C. The sol-gel layer may be thermally cured at about 70,75, 80, 85, or 90° C., where any value may form an upper end point or alower end point, as appropriate. The thermal curing may be performed fora time period ranging from about 40 to about 120 minutes. The timeperiod may be 40, 50, 60, 70, 80, 90, 100, 110, or 120 min, where anyvalue may form an upper end point or a lower end point, as appropriate.In an example, the thermal curing is performed in a hot air circulatedoven. Alternatively, or in addition to, thermal curing at a hightemperature, the thermal curing includes exposing the sol-gel layer toinfrared (IR) radiation, near IR radiation, and/or microwave radiation.For example, the sol-gel layer is exposed to IR and/or near IR radiationfor a time period ranging from about 10 to about 60 min (e.g., 30 min orother time period). The time period of exposure to IR and/or near IR maybe about 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, or 60 min, where anyvalue may form an upper end point or a lower end point, as appropriate.

At block 308, primer and/or paint is applied on the sol-gel layer of thesubstrate. For example, the primer is applied on the sol-gel layer, andthe paint is applied on the primer. Advantageously, the cured sol-gellayer not only provides corrosion resistance to the substrate but alsofacilitates adherence of the primer and/or paint to the substrate.

FIG. 4 illustrates a diagrammatic cross-sectional view of an examplecorrosion-resistant coating on a substrate 402 formed, for example, byprocess 300 of FIG. 3 . The corrosion-resistant coating includes aCIM-containing sol gel layer 404 formed on substrate 402. CIM-containingsol gel layer 404 includes sol-gel composition and a corrosioninhibiting material. The corrosion inhibiting material includes alayered metal phosphate composition (e.g., a layered tetravalentphosphate composition) that provides nanocarriers of layered tetravalentmetal phosphate, and a corrosion inhibitor intercalated in thenanocarriers of layered tetravalent metal phosphate.

In other embodiments, the corrosion-resistant coating includes aplurality of CIM-containing sol gel layers, one of which may be aCIM-containing sol gel layer formed from a sol-gel composition thatcontains a corrosion inhibitor-intercalated layered metal phosphatecomposition prepared according to process 200 of FIG. 2 . One or more ofthe other sol gel layers may include a different corrosion inhibitingmaterial such as a corrosion inhibitor-encapsulated layered doublehydroxide (LDH) composition formed by a process 500 of FIG. 5 ,described further below. Further, at least one of the other sol gellayers may not include a corrosion inhibiting material.

FIG. 5 illustrates an example process 500 for preparing a corrosioninhibiting material that includes an LDH composition (e.g., a Zn—Al LDHcomposition) encapsulating one or more corrosion inhibitors. Thecorrosion inhibiting material may be an organic corrosion inhibitingmaterial that includes one or more organic corrosion inhibitors, aninorganic corrosion inhibiting material that includes one or moreorganic corrosion inhibitors, or a combination corrosion inhibitingmaterial that includes one or more organic corrosion inhibitors and oneor more inorganic corrosion inhibitors.

At block 502, a solution of corrosion inhibitor is prepared. Forexample, an organic corrosion inhibitor is dissolved or dispersed in asolvent to form the solution. In another example, an inorganic corrosioninhibitor is dissolved in a solvent to form the solution. In a furtherexample, an organic corrosion inhibitor and an inorganic corrosioninhibitor is dissolved in a solvent to form the solution.

In an aspect, the organic corrosion inhibitor is an imidazole, atriazole, a tetrazole, a thiazole, a thiadiazole, a benzimidazole, abenzotriazole, a benzothiazole, a quinoline, phytic acid, anorganophosphonic acid, or an oil. The oil includes saturated and/orunsaturated fatty acids such as stearic acid, palmitic acid, oleic acid,linoleic acid, and/or linolenic acid.

Specific examples of the organic corrosion inhibitor include1-(3-aminopropyl)imidazole, 1H-1,2,3-triazole,4-methyl-4H-1,2,4-triazole-3-thiol, 1,2,4-triazole-3-carboxylic acid,3-amino-1,2,4-triazole-5-thiol, 4H-1,2,4-triazol-4-amine,3-mercapto-4-methyl-4H-1,2,4-triazole,5-phenyl-1H-1,2,4-triazole-3-thiol, 1-methyl-1H-tetrazole-5-thiol,1H-tetrazole-5-acetic acid, 4-methyl-1,3-thiazole-5-carboxylic acid,1,3,4-thiadiazole-2,5-dithiol, 1H-benzimidazole-2-carboxylic acid,1H-benzotriazole (BTA), 2-mercaptobenzothiazole (MBT),8-hydroxyquinoline, phytic acid, amino tris(methylenephosphonic acid)(ATMP), ethylenediamine tetra(methylenephosphonic acid) (EDTMP),1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), diethylenetriaminepenta(methylenephosphonic acid) (DTPMP), and a vegetable oil (e.g.,linseed oil or other vegetable oil).

In an aspect, the inorganic corrosion inhibitor is a salt of an oxyanionof a transition metal, a post-transition metal, a metalloid, or apolyatomic non-metal. In another aspect, the inorganic corrosioninhibitor is a vanadate, a molybdate, a tungstate, a phosphate, amanganate, a permanganate, or an aluminate.

Specific examples of the inorganic corrosion inhibitor include sodiummetavanadate, potassium permanganate, sodium molybdate, and sodiumtungstate.

At block 504, a Zn—Al LDH composition is prepared. For example, theZn—Al LDH compound may be prepared by a process 600 of FIG. 6 .

At block 506, the Zn—Al LDH composition is added to the solution of thecorrosion inhibitor. For example, the Zn—Al LDH composition in an amountranging from about 5 to about 100 g per 1 L of the solution is added tothe solution with stirring and stirring is continued for a time periodranging from 3 to about 48 h. The amount of the Zn—Al LDH compositionmay be 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80,85, 90, 95, or 100 g per 1 L of the solution, where any value may forman upper end point or a lower end point, as appropriate. The time periodmay be about 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 45, or48 h, where any value may form an upper end point or a lower end point,as appropriate. A corrosion inhibitor encapsulated LDH precipitate isformed as a result of block 506. The Zn—Al LDH is intercalated with thecorrosion inhibitor such that the Zn—Al LDH composition functions asnanocontainers that encapsulate the corrosion inhibitor.

At block 508, the precipitate of the solution of the corrosion inhibitoris collected, for example, by centrifugation. The precipitate is washedat block 510 and dried at block 512 to form the corrosion inhibitingmaterial. For example, the precipitate is washed with hot water untilthe pH of the supernatant is neutral, and then dried in a drying oven.The corrosion inhibiting material includes a corrosioninhibitor-exchanged Zn—Al LDH composition (also referred to as acorrosion inhibitor-incorporated Zn—Al LDH composition, a corrosioninhibitor-intercalated Zn—Al LDH composition or a corrosioninhibitor-encapsulated Zn—Al LDH composition).

If an organic corrosion inhibitor is used in block 502, the corrosioninhibiting material is an organic corrosion inhibiting material thatincludes the organic corrosion inhibitor encapsulated in the Zn—Al LDHcomposition. If an inorganic corrosion inhibitor is used in block 502,the corrosion inhibiting material is an organic corrosion inhibitingmaterial that includes the organic corrosion inhibitor encapsulated inthe Zn—Al LDH composition. Accordingly, in embodiments in which both aninorganic corrosion inhibiting material and an organic corrosioninhibiting material are desired, process 500 may be performed twice,once using an organic corrosion inhibitor at block 102 and once using aninorganic corrosion inhibitor at block 502.

In some embodiments, a combination corrosion inhibiting material thatincludes the Zn—Al LDH composition encapsulating both an organiccorrosion inhibitor and an inorganic corrosion inhibitor may be formedby mixing an organic corrosion inhibiting material and an inorganiccorrosion inhibitor each prepared by respective process 500, or bypreparing a solution including both types of corrosion inhibitors atblock 502 in one process 500.

FIG. 6 illustrates an example process 600 for preparing a Zn—Al LDHcomposition. For example, block 504 of FIG. 5 may be performed byprocess 600.

At block 602, a solution of a zinc salt (e.g., zinc nitrate or otherzinc salt) and a solution of aluminum salt (e.g., aluminum nitrate orother aluminum salt) is mixed to form a solution of zinc and aluminum.For example, zinc nitrate is dissolved in a solvent, aluminum nitrate isdissolved in a solvent, and the zinc nitrate solution and the aluminumsolution is mixed and stirred under nitrogen purging to form thesolution of zinc and aluminum, also referred to as a mixture.

At block 604, a solution of an alkali metal salt such as a sodium salt(e.g., sodium nitrate or other sodium salt) is added to the mixture. Forexample, a solution of sodium nitrate is added drop-wise to the mixturewhile maintaining a pH ranging from about 8 to about 11 using a basesolution (e.g., a 2.0 M sodium hydroxide solution or other basesolution). The maintained pH may be about 8, 8.5, 9, 9.5, 10, 10.5, or11, where any value may form an upper end point or a lower end point, asappropriate. A fluffy white precipitate is formed in the resultingmixture. Once the addition of the sodium nitrate solution is complete,the mixture is stirred vigorously under nitrogen purging for a timeperiod ranging from about 3 to 24 h. The time period may be about 3, 6,9, 12, 15, 18, 21, or 24 h, where any value may form an upper end pointor a lower end point, as appropriate.

At block 608, the precipitate of the mixture is collected, for example,by centrifugation. The precipitate is washed at block 610 and dried atblock 612 to form the Zn—Al LDH composition. For example, theprecipitate is washed with hot water and then dried in a drying oven.

FIG. 7 illustrates an example process 700 for forming acorrosion-resistant coating that includes one or more sol-gel layers(e.g., one or more sol-gel coatings) on a substrate such as a panel(e.g., an aluminum substrate, an aluminum alloy substrate, or othersubstrate). One or more layers of the sol-gel composition are applied toa substrate, each of the one or more layers is cured by UV light, andthen the one or more layers of the sol-gel composition are thermallycured.

At block 702, a first sol-gel composition prepared by process 200 ofFIG. 2 (e.g., a CIM-containing compound with a corrosioninhibitor-encapsulated layered metal phosphate composition, aCIM-containing compound with a corrosion inhibitor-encapsulated Zn—AlLDH composition, or a sol-gel composition without a corrosion inhibitingmaterial) is applied to a substrate. For example, the first sol-gelcomposition is contacted with the substrate to form a sol-gel layer suchas by dipping the substrate in the first sol-gel composition, byimmersing the substrate in the first sol-gel composition, by sprayingthe first sol-gel composition on the substrate, and/or by other methodsof applying the first sol-gel composition to the substrate. If dipcoating is used, the sol-gel layer can be deposited using a withdrawalsspeed ranging from about 1 to about 15 mm/s (e.g., about 5 to about 12mm/s, about 10 mm/s, or other withdrawal speed). The withdrawal speedmay be about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 mm/s,where any value may form an upper end point or a lower end point, asappropriate.

At block 704, the sol-gel layer formed by block 702 is cured by UVradiation. For example, the UV radiation has a light dose ranging fromabout 500 to about 1000 mJ/cm². The UV radiation may have a light doseof about 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, or 1000mJ/cm², where any value may form an upper end point or a lower endpoint, as appropriate. The curing by UV radiation may be performed for atime period ranging from about 0.5 to about 30 min. The time period maybe about 0.5, 1, 2, 3, 4, 5, 10, 15, 20, 25, or 30 min, where any valuemay form an upper end point or a lower end point, as appropriate.

At block 706, a second sol-gel composition prepared by process 200 ofFIG. 2 (e.g., a CIM-containing compound with a corrosioninhibitor-encapsulated layered metal phosphate composition, aCIM-containing compound with a corrosion inhibitor-encapsulated Zn—AlLDH composition, or a sol-gel composition without a corrosion inhibitingmaterial) is applied to the substrate (e.g., on a previously formed solgel layer on the substrate). For example, the second sol-gel compositionis contacted with the substrate to form a sol-gel layer such as bydipping the substrate in the second sol-gel composition, by immersingthe substrate in the second sol-gel composition, by spraying the secondsol-gel composition on the substrate, and/or by other methods ofapplying the second sol-gel composition to the substrate. If dip coatingis used, the second sol-gel layer can be deposited using a withdrawalsspeed ranging from about 1 to about 15 mm/s (e.g., about 5 to about 12mm/s, about 10 mm/s, or other withdrawal speed). The withdrawal speedmay be about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 mm/s,where any value may form an upper end point or a lower end point, asappropriate.

At block 708, the sol-gel layer formed by block 706 is cured by UVradiation. For example, the UV radiation has a light dose ranging fromabout 500 to about 1000 mJ/cm². The UV radiation may have a light doseof about 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, or 1000mJ/cm², where any value may form an upper end point or a lower endpoint, as appropriate. The curing by UV radiation may be performed for atime period ranging from about 0.5 to about 30 min. The time period maybe about 0.5, 1, 2, 3, 4, 5, 10, 15, 20, 25, or 30 min, where any valuemay form an upper end point or a lower end point, as appropriate.

In some embodiments, blocks 706-708 are repeated to form one or moreadditional sol-gel layers. Blocks 706-708 may be repeated with the sameor different type of sol-gel composition until the desired sol-gellayers are formed. In some embodiments, block 704 and/or 708 may beomitted for at least one of the sol-gel layers (e.g., at least one ofthe sol-gel layers may be air dried or thermally cured instead of curingusing UV radiation). For example, curing using UV radiation may beomitted for the final, top-most sol-gel layer among the desired sol-gellayers. At least one of the sol-gel layers are formed from theCIM-containing sol-gel layer with the corrosion inhibitor-encapsulatedlayered metal phosphate composition.

At block 710, the sol-gel layers are thermally cured. For example, themultiple sol-gel layers are thermally cured at a temperature rangingfrom about 70 to about 90° C. The multiple sol-gel layers may bethermally cured at about 70, 75, 80, 85, or 90° C., where any value mayform an upper end point or a lower end point, as appropriate. Thethermal curing may be performed for a time period ranging from about 40to about 120 minutes. The time period may be 40, 50, 60, 70, 80, 90,100, 110, or 120 min, where any value may form an upper end point or alower end point, as appropriate. In an example, the thermal curing isperformed in a hot air circulated oven. Alternatively, or in additionto, thermal curing at a high temperature, the thermal curing includesexposing the sol-gel layers to infrared (IR) radiation, near IRradiation, and/or microwave radiation. For example, the sol-gel layersare exposed to IR and/or near IR radiation for a time period rangingfrom about 10 to about 60 min (e.g., 30 min or other time period). Thetime period of exposure to IR and/or near IR may be about 10, 15, 20,25, 30, 35, 40, 45, 50, 55, or 60 min, where any value may form an upperend point or a lower end point, as appropriate.

At block 712, primer and/or paint is applied on the sol-gel layers ofthe substrate. For example, the primer is applied on the top-mostsol-gel layer, and the paint is applied on the primer. Advantageously,the cured sol-gel layers not only provide corrosion resistance to thesubstrate but also facilitate adherence of the primer and/or paint tothe substrate.

FIGS. 8A-F illustrate diagrammatic cross-sectional views of examplecorrosion-resistant coatings that include a plurality of sol-gel layersformed on substrates 800, 810, 820, 830, 840, 850 by process 700 of FIG.7 . FIG. 8A shows a corrosion-resistant coating that includes a sol-gellayer 802 containing a corrosion inhibitor intercalated in a layeredzirconium phosphate (Zr—P) composition formed on substrate 800, and asol-gel layer 804 containing a corrosion inhibitor intercalated in aZn—Al LDH composition formed on sol-gel layer 802. FIG. 8B shows acorrosion-resistant coating that includes a sol-gel layer 812 containinga corrosion inhibitor intercalated in a Zn—Al LDH composition formed onsubstrate 810, and a sol-gel layer 814 containing a corrosion inhibitorintercalated in a layered zirconium phosphate composition formed onsol-gel layer 812.

FIG. 8C shows a corrosion-resistant coating that includes a sol-gellayer 822 containing a corrosion inhibitor intercalated in a layeredzirconium phosphate composition formed on substrate 820, and a sol-gellayer 824 containing the same or a different corrosion inhibitorintercalated in a layered zirconium phosphate composition formed onsol-gel layer 822. FIG. 8D shows a corrosion-resistant coating thatincludes a sol-gel layer 832 that does not contain a corrosion inhibitorformed on substrate 830, and a sol-gel layer 834 containing a corrosioninhibitor intercalated in a layered zirconium phosphate compositionformed on sol-gel layer 832.

FIG. 8E shows a corrosion-resistant coating that includes a sol-gellayer 842 containing a corrosion inhibitor intercalated in a layeredzirconium phosphate composition formed on substrate 840, and a sol-gellayer 844 that does not contain a corrosion inhibitor formed on sol-gellayer 842. FIG. 8F shows a corrosion-resistant coating that includes asol-gel layer 852 that does not contain a corrosion inhibitor formed onsubstrate 850, a sol-gel layer 854 containing a corrosion inhibitorintercalated in a layered zirconium phosphate composition formed onsol-gel layer 852, and a sol-gel layer 856 that does not contain acorrosion inhibitor formed on sol-gel layer 854.

The following examples are provided to illustrate certain aspects of theprocesses and formulations relating to sol-gel coatings, and are notintended to limit the invention in any manner.

Example 1

An α-zirconium phosphate composition was formed. A zirconyl chloride(ZrOCl₂.8H₂O) solution having a concentration of about 0.05 M in theamount of about 120 ml was mixed with a phosphoric acid (H₃PO₄) solutionhaving a concentration of about 6 M in the amount of about 85 ml wasmixed with constant stirring at about 94° C. for about 48 h. Theprecipitate was centrifuged and washed repeatedly with water to form apowder of α-zirconium phosphate. FIG. 9 shows an X-ray powderdiffraction (XRD) pattern of the α-zirconium phosphate. FIG. 10A andFIG. 10B show scanning electron microscope (SEM) images of theα-zirconium phosphate at low magnification and at high magnification,respectively, illustrating the layered sheet like structure of theα-zirconium phosphate.

Example 2

A sol-gel composition was prepared according to process 200 of FIG. 2 .Composition A was synthesized by mixing about 171.5 g of3-methacryloxypropyltrimethoxysilane and about 17.0 g of water in aglass jar loaded on a magnetic stirrer. About 5.5 grams of 0.1 N HCl wasfurther added to the mixture. The solution was stirred in an ice bathtill the solution turned transparent. Although3-methacryloxypropyltrimethoxysilane was used in this example, one ormore other alkoxysilanes of Formula IV may be used in place of, or inaddition to, 3-methacryloxypropyltrimethoxysilane in other examples.Also, although HCl was used in this example, one or more other inorganicacids may be used in place of, or in addition to, HCl in other examples.

Composition B was synthesized by mixing about 11.8 g of methacrylic acidand about 45.2 g of zirconium n-propoxide under vigorous stirring.Stirring was continued for about 2 h. Although zirconium n-propoxide wasused in this example, one or more other zirconium alkoxides of Formula Vmay be used in place of, or in addition to, zirconium n-propoxide inother examples.

Composition B was added to composition A under vigorous stirring toavoid agglomeration by placing the mixture in an ice bath, and themixture was stirred for about 1 h. The jar containing the mixture wasremoved from the ice bath and stirred at room temperature for at least 1hour for the mixture to come to room temperature.

Then about 100 g of phenyltrimethoxysilane was added to the mixture ofComposition A and Composition B and stirred for about 1 h, and thenabout 100 g of 3-aminopropyltrimethoxysilane was added and stirred forabout 1 hour. After completion of the stirring with3-aminopropyltrimethoxysilane, about 25 grams of3-glycidoxypropyltrimethoxysilane was added. Finally, about 10 grams ofmethacrylic acid was added followed by about 4 g of 0.1 N HCl andstirred for a further duration of about 1 h. Althoughphenyltrimethoxysilane, 3-aminopropyltrimethoxysilane, and3-glycidoxypropyltrimethoxysilane were used in this example, one or moreother methoxysilanes of Formula VI may be used in place of, or inaddition to, phenyltrimethoxysilane, 3-aminopropyltrimethoxysilane,and/or 3-glycidoxypropyltrimethoxysilane in other examples.

The resulting mixture was diluted with isopropanol in a weight ratio ofabout 1:1 and stirred for about 3 h at room temperature for aging.Although the mixture was stirred for about 3 h, the mixture may be agedfor a different time period in other examples, such as stirringovernight. About 1 kg of sol-gel composition ready for coatingapplication was formed. A photoinitiator, IRGACURE® 184, in the amountof about 2% by weight per 100% of the sol-gel composition (including thephotoinitiator) was added and stirred for about 30 min. AlthoughIRGACURE® 184 was used in this example, one or more otherphotoinitiators may be used in place of, or in addition to, IRGACURE®184 in other examples. After adding IRGACURE® 184, the sol-gelcomposition was kept away from light to avoid the sol-gel compositionfrom interacting with light. The solid content of the sol-gelcomposition was about 28 parts by weight per 100 parts by weight of thesol-gel composition (including the photoinitiator).

Example 3

A sol-gel composition that includes a layered α-zirconium phosphatecomposition (without a corrosion inhibitor intercalated) was preparedaccording to process 200 of FIG. 2 . A layered α-zirconium phosphatecomposition, prepared as described in Example 1, was added to a sol-gelcomposition prepared as described in Example 2. To add 5 parts by weightof the layered α-zirconium phosphate composition per 100 parts by weightof the solid content of the sol-gel composition, about 1.4 g of thelayered α-zirconium phosphate composition was added per 100 g of thesol-gel composition and stirred overnight. Although the stirring wascarried out overnight in this example, other time periods may be used inother examples (e.g., about 2 h may be sufficient for uniformdispersion).

Example 4

A corrosion inhibiting material including a vanadate-intercalatedlayered α-zirconium phosphate composition was prepared according toprocess 100 of FIG. 1 . An α-zirconium phosphate composition, preparedas described in Example 1, in an amount of about 3 g and sodiummetavanadate (NaVO₃) in an amount of about 1.292 g were added to about325 ml of water and stirred for about 16 h. Although sodium metavanadatewas used in this example, other corrosion inhibitors may be used inplace of, or in addition to, sodium metavanadate in other examples. Theresulting solution was centrifuged and the powder obtained wasrepeatedly washed with water until a neutral pH was obtained to form avanadate-intercalated layered α-zirconium phosphate. FIG. 12 shows anXRD pattern of the vanadate-intercalated layered α-zirconium phosphate.

Example 5

A sol-gel composition that includes a vanadate-intercalated layeredα-zirconium phosphate composition was prepared according to process 200of FIG. 2 . A vanadate-intercalated layered α-zirconium phosphatecomposition, prepared as described in Example 4, was added as acorrosion inhibiting material to a sol-gel composition, prepared asdescribed in Example 2, to form a CIM-containing sol-gel composition.Although the vanadate-intercalated layered α-zirconium phosphatecomposition was used in this example, other corrosion inhibitingmaterials may be used in other examples. To add 5 parts by weight of thecorrosion inhibiting material per 100 parts by weight of the solidcontent of the sol-gel composition, about 1.4 g of thevanadate-intercalated layered α-zirconium phosphate composition wasadded per 100 g of the sol-gel composition and stirred overnight.Although the stirring was carried out overnight in this example, othertime periods may be used in other examples (e.g., about 2 h may besufficient for uniform dispersion).

Example 6

A corrosion inhibiting material including a cerium-intercalated layeredα-zirconium phosphate composition was prepared according to process 100of FIG. 1 . An α-zirconium phosphate composition, prepared as describedin Example 1, in an amount of about 3 g and cerium nitrate hexahydrate(Ce(NO₃)₃.6H₂O) in an amount of about 4.601 g were added to about 325 mlof water and stirred for about 16 h. Although cerium nitrate hexahydratewas used in this example, other corrosion inhibitors may be used inplace of, or in addition to, cerium nitrate hexahydrate in otherexamples. The resulting solution was centrifuged and the powder obtainedwas repeatedly washed with water until a neutral pH was obtained to forma cerium-intercalated layered α-zirconium phosphate. FIG. 1 shows an XRDpattern of the cerium-intercalated layered α-zirconium phosphate.

Example 7

A sol-gel composition that includes a cerium-intercalated layeredα-zirconium phosphate composition was prepared according to process 200of FIG. 2 . A cerium-intercalated layered α-zirconium phosphatecomposition, prepared as described in Example 6, was added as acorrosion inhibiting material to a sol-gel composition, prepared asdescribed in Example 2, to form a CIM-containing sol-gel composition.Although the cerium-intercalated layered α-zirconium phosphatecomposition was used in this example, other corrosion inhibitingmaterials may be used in other examples. To add 5 parts by weight of thecorrosion inhibiting material per 100 parts by weight of the solidcontent of the sol-gel composition, about 1.4 g of thecerium-intercalated layered α-zirconium phosphate composition was addedper 100 g of the sol-gel composition and stirred overnight. Although thestirring was carried out overnight in this example, other time periodsmay be used in other examples (e.g., about 2 h may be sufficient foruniform dispersion).

Example 8

A Zn—Al LDH composition was formed according to process 600 of FIG. 6 .A solution of about 104.1 g of zinc nitrate hexahydrate (Zn(NO₃)₂·6H₂O)dissolved in about 25 ml water and a solution of about 65.6 g ofaluminum nitrate nonahydrate (Al(NO₃)₃.9H₂O) dissolved in about 25 mlwater was mixed under vigorous stirring under N₂ purging. To thismixture, about 87.5 ml of a NaNO₃ solution having a concentration ofabout 0.1 M, adjusted to a pH of about 10, was added drop-wise andmaintained at a pH of about 10 by adding a NaOH having a concentrationof about 2.0 M. A fluffy LDH white precipitate was formed. Once theaddition was complete, the entire mixture was stirred vigorously underN₂ purging for about 12 h. The precipitate was centrifuged at about 6500rpm and washed about 3 or 4 times with hot water (at 80° C.), followedby drying at about 65° C. for about 24 h. A Zn—Al LDH composition in theform of a powder was formed.

Example 9

A corrosion inhibiting material including a vanadate-intercalated Zn—AlLDH composition was formed according to process 500 of FIG. 5 . A sodiummetavanadate solution having a concentration of about 0.1 M in theamount of about 400 ml was prepared. The pH of this solution wasadjusted to a pH ranging from about 8 to about 9 by addition of a NaOHsolution having a concentration of about 2.0 M. To this, about 10 g of aZn—Al LDH composition, prepared as described in Example 8, was addedwith continuous stirring. Stirring was continued for about 24 h. Thesolution was then centrifuged to obtain a powder. The powder was washedwith hot water until the pH of the supernatant was neutral, and followedby drying the vanadate-exchanged Zn—Al LDH composition at about 60° C.for a time period ranging from about 3 to about 4 h in a drying oven.Other corrosion inhibiting materials may be prepared using other organiccorrosion inhibitors or inorganic corrosion inhibitors in otherexamples.

Example 10

A sol-gel composition that includes a vanadate-intercalated Zn—Al LDHcomposition was prepared according to process 200 of FIG. 2 . Avanadate-intercalated Zn—Al LDH composition, prepared as described inExample 9, was added as a corrosion inhibiting material to a sol-gelcomposition, prepared as described in Example 2, to form aCIM-containing sol-gel composition. Although the vanadate-intercalatedZn—Al LDH composition was used in this example, other corrosioninhibiting materials may be used in other examples. To add 5 parts byweight of the corrosion inhibiting material per 100 parts by weight ofthe solid content of the sol-gel composition, about 1.4 g of thevanadate-intercalated Zn—Al LDH composition was added per 100 g of thesol-gel composition and stirred overnight. Although the stirring wascarried out overnight in this example, other time periods may be used inother examples (e.g., about 2 h may be sufficient for uniformdispersion).

Example 11

A corrosion inhibiting material including a linseed oil-intercalatedZn—Al LDH composition was formed according to process 500 of FIG. 5 . AZn—Al LDH composition, prepared as described in Example 8, was added toa solution containing linseed oil with continuous stirring. Stirring wascontinued for about 24 h. The solution was then centrifuged to obtain apowder. The powder was washed with hot water until the pH of thesupernatant was neutral, and followed by drying the linseedoil-exchanged Zn—Al LDH composition at about 60° C. for a time periodranging from about 3 to about 4 h in a drying oven. Other corrosioninhibiting materials may be prepared using other organic corrosioninhibitors or inorganic corrosion inhibitors in other examples.

Example 12

A sol-gel composition that includes a linseed oil-intercalated Zn—Al LDHcomposition was prepared according to process 200 of FIG. 2 . A linseedoil-intercalated Zn—Al LDH composition, prepared as described in Example11, was added as a corrosion inhibiting material to a sol-gelcomposition, prepared as described in Example 2, to form aCIM-containing sol-gel composition. Although the linseedoil-intercalated Zn—Al LDH composition was used in this example, othercorrosion inhibiting materials may be used in other examples. To add 5parts by weight of the corrosion inhibiting material per 100 parts byweight of the solid content of the sol-gel composition, about 1.4 g ofthe linseed oil-intercalated Zn—Al LDH composition was added per 100 gof the sol-gel composition and stirred overnight. Although the stirringwas carried out overnight in this example, other time periods may beused in other examples (e.g., about 2 h may be sufficient for uniformdispersion).

Example 13

The following coated panels were generated by contacting each panel withrespective sol-gel composition(s):

Panel 1: A single layer of a sol-gel composition containing a layeredzirconium phosphate compound (without intercalated corrosion inhibitor)prepared as described in Example 3.

Panel 2: A single layer of a sol-gel composition containing avanadate-intercalated layered zirconium phosphate composition preparedas described in Example 5.

Panel 3: A single layer of a sol-gel composition containingcerium-intercalated layered zirconium phosphate composition prepared asdescribed in Example 7.

Panel 4: A double layer including a layer of a sol-gel compositioncontaining layered zirconium phosphate (without intercalated corrosioninhibitor) prepared as described in Example 3, and a layer of a sol-gelcomposition containing a vanadate-intercalated LDH composition preparedas described in Example 10.

Panel 5: A double layer including a layer of a sol-gel compositioncontaining vanadate-intercalated layered zirconium phosphate compositionprepared as described in Example 5, and a layer of a sol-gel compositioncontaining a vanadate-intercalated LDH composition prepared as describedin Example 10.

Panel 6: A double layer including a layer of a sol-gel compositioncontaining cerium-intercalated layered zirconium phosphate compositionprepared as described in Example 7, and a layer of a sol-gel compositioncontaining a vanadate-intercalated LDH composition prepared as describedin Example 10.

Panel 7: A double layer including a layer of a sol-gel compositioncontaining linseed oil-intercalated layered zirconium phosphatecomposition prepared as described in Example 12, and a layer of asol-gel composition containing a vanadate-intercalated layered zirconiumphosphate composition prepared as described in Example 5.

Panel 8: A double layer including a layer of a sol-gel compositioncontaining linseed oil-intercalated layered zirconium phosphatecomposition prepared as described in Example 12, and a layer of asol-gel composition containing a cerium-intercalated layered zirconiumphosphate composition prepared as described in Example 7.

Each sol-gel layer was UV cured using a conveyorized UV curing unit. UVcuring was performed using a conveyorized UV curing unit with threemedium-pressure mercury lamps. The lamps (about 1 m long) provided anoutput of about 120 W/cm with a total wattage/lamp of about 12 kW. Thebelt speed was maintained at about 2 m/min during curing. The light doseas measured by a UV radiometer was about 871 mJ/cm² in the UV-C region.After UV curing each layer for about 5 minutes, the coated panel wassubjected to thermal curing in an air circulated oven at about 80° C.for about an hour.

Example 14

Each of Panels 1-8 of Example 13 was subjected to a salt spray test totest for corrosion, in which each panel was exposed to a 5% salt spray.An uncoated panel was also subject to the salt spray test. FIG. 13 showsa panel after about 336 h of the salt spray test, which showed severecorrosion. Coatings that included a corrosion inhibitor-intercalatedlayered zirconium phosphate compound as its corrosion inhibitingmaterial performed better than coatings that included layered zirconiumphosphate without an intercalated corrosion inhibitor. Further, thedouble layered coatings of Panels 4-8 performed better than the singlelayered coatings of Panels 1-3.

FIG. 14A and FIG. 14B show Panel 4 after about 168 h of the salt spraytest and after about 336 h of the salt spray test, respectively.

FIG. 15A and FIG. 15B show Panel 5 after about 168 h of the salt spraytest and after about 336 h of the salt spray test, respectively.

FIG. 16A and FIG. 16B show Panel 6 after about 168 h of the salt spraytest and after about 336 h of the salt spray test, respectively.

FIG. 17A and FIG. 17B show Panel 7 after about 168 h of the salt spraytest and after about 336 h of the salt spray test, respectively.

FIG. 18A and FIG. 18B show Panel 8 after about 168 h of the salt spraytest and after about 336 h of the salt spray test, respectively.

Very few corrosion pits developed on Panels 4-8 as shown in thesefigures compared to the uncoated panel of FIG. 13 . Among all thepanels, Panels 7 and 8 were the most corrosion resistant, as theyadvantageously were pit-free up to 168 h and had very little pit densityafter 336 h.

When introducing elements of the present invention or exemplary aspectsor embodiment(s) thereof, the articles “a,” “an,” “the,” and “said” areintended to mean that there are one or more of the elements. The terms“comprising,” “including,” and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements. Although this invention has been described with respect tospecific embodiments, the details of these embodiments are not to beconstrued as limitations. Different aspects, embodiments and featuresare defined in detail herein. Each aspect, embodiment or feature sodefined may be combined with any other aspect(s), embodiment(s) orfeature(s) (preferred, advantageous or otherwise) unless clearlyindicated to the contrary. Accordingly, the scope of the invention isdefined only by the following claims.

What is claimed is:
 1. A first corrosion-inhibiting material (CIM)comprising: a layered tetravalent metal phosphate composition comprisingnanoparticles of layered tetravalent metal phosphate, each nanoparticleof layered tetravalent metal phosphate having a size ranging from about1 nm to about 1000 nm; and a first corrosion inhibitor intercalated inthe nanoparticles of layered tetravalent metal phosphate, wherein thefirst corrosion inhibitor comprises cerium (III), a vanadate, amolybdate, a tungstate, a manganate, a permanganate, an aluminate, athiazole, a triazole, an imidazole, or a combination thereof.
 2. Thefirst CIM of claim 1, wherein the layered tetravalent metal phosphatecomprises layered zirconium phosphate.
 3. The first CIM of claim 2,wherein the layered zirconium phosphate comprises Zr(HPO₄)₂·H₂O orZr(PO₄)(H₂PO₄)·2H₂O.
 4. A first sol-gel composition, comprising: thefirst CIM of claim 1; and a first polymer composite of one or morealkoxysilanes, a zirconium alkoxide, and an organic acid.
 5. The firstsol-gel composition of claim 4, wherein the one or more alkoxysilanescomprise an alkoxysilane having formula R_(A)—Si—(R_(B))₃, wherein R_(A)is methacryloxyalkyl or glycidyloxyalkyl and R_(B) is a methoxy orethoxy, an alkoxysilane having formula R_(D)—Si—(R_(E))₃, wherein R_(D)is aryl, aminoalkyl, or glycidoxyalkyl and R_(E) is methoxy or ethoxy,or a combination thereof.
 6. The first sol-gel composition of claim 4,wherein the zirconium alkoxide has a formula Zr—(R_(C))₄, wherein R_(C)is ethoxy, n-propoxy, isopropoxy, n-butyloxy, or tert-butyloxy.
 7. Thefirst sol-gel composition of claim 4, wherein the organic acid comprisesacrylic acid, methacrylic acid (MAA), ethacrylic acid, crotonic acid,itaconic acid, maleic acid, or fumeric acid.
 8. A corrosion-resistantcoated product, comprising: a first CIM-containing sol-gel layercomprising the first sol-gel composition of claim
 4. 9. Thecorrosion-resistant coated product of claim 8, further comprising: asecond CIM-containing sol-gel layer comprising a second CIM and a secondpolymer composite of one or more alkoxysilanes, a zirconium alkoxide,and an organic acid; wherein the second CIM comprises: a Zn—Al layereddouble hydroxide (LDH) composition comprising nanoparticles of Zn—AlLDH, each nanoparticle of Zn—Al LDH having a size ranging from about 1nm to about 1000 nm; and a second corrosion inhibitor intercalated inthe nanoparticles of the Zn—Al LDH, the second corrosion inhibitor. 10.The corrosion-resistant coated product of claim 9, wherein the secondcorrosion inhibitor comprises 1-(3-aminopropyl)imidazole,1H-1,2,3-triazole, 4-methyl-4H-1,2,4-triazole-3-thiol,1,2,4-triazole-3-carboxylic acid, 3-amino-1,2,4-triazole-5-thiol,4H-1,2,4-triazol-4-amine, 3-mercapto-4-methyl-4H-1,2,4-triazole,5-phenyl-1H-1,2,4-triazole-3-thiol, 1-methyl-1H-tetrazole-5-thiol,1H-tetrazole-5-acetic acid, 4-methyl-1,3-thiazole-5-carboxylic acid,1,3,4-thiadiazole-2,5-dithiol, 1H-benzimidazole-2-carboxylic acid,1H-benzotriazole (BTA), 2-mercaptobenzothiazole (MBT),8-hydroxyquinoline, phytic acid, an organophosphonic acid, a vegetableoil, a vanadate, a molybdate, a tungstate, a phosphate, a manganate, apermanganate, an aluminate, or a combination thereof.
 11. Thecorrosion-resistant coated product of claim 9, further comprising aprimer, a paint, or a combination thereof on the second CIM-containingsol-gel layer.
 12. A first corrosion-inhibiting material (CIM)comprising: a layered tetravalent metal phosphate composition comprisingnanoparticles of layered tetravalent metal phosphate, each nanoparticleof layered tetravalent metal phosphate having a size ranging from about1 nm to about 1000 nm; and a first corrosion inhibitor intercalated inthe nanoparticles of layered tetravalent metal phosphate, wherein thefirst corrosion inhibitor comprises cerium (III), a vanadate comprisingsodium metavanadate, a molybdate comprising sodium molybdate, atungstate comprising sodium tungstate, a manganate, a permanganatecomprising potassium permanganate, an aluminate, a thiazole, a triazole,an imidazole, or a combination thereof.
 13. The first CIM of claim 12,wherein the layered tetravalent metal phosphate comprises layeredzirconium phosphate.
 14. A first sol-gel composition, comprising: thefirst CIM of claim 12; and a first polymer composite of one or morealkoxysilanes, a zirconium alkoxide, and an organic acid.
 15. The firstsol-gel composition of claim 14, wherein the one or more alkoxysilanescomprise an alkoxysilane having formula R_(A)—Si—(R_(B))₃, wherein R_(A)is methacryloxyalkyl or glycidyloxyalkyl and R_(B) is a methoxy orethoxy, an alkoxysilane having formula R_(D)—Si—(R_(E))₃, wherein R_(D)is aryl, aminoalkyl, or glycidoxyalkyl and R_(E) is methoxy or ethoxy,or a combination thereof.
 16. The first sol-gel composition of claim 14,wherein the zirconium alkoxide has a formula Zr—(R_(C))₄, wherein R_(C)is ethoxy, n-propoxy, isopropoxy, n-butyloxy, or tert-butyloxy.
 17. Thefirst sol-gel composition of claim 14, wherein the organic acidcomprises acrylic acid, methacrylic acid (MAA), ethacrylic acid,crotonic acid, itaconic acid, maleic acid, or fumeric acid.
 18. Acorrosion-resistant coated product, comprising: a first CIM-containingsol-gel layer comprising the first sol-gel composition of claim
 14. 19.The corrosion-resistant coated product of claim 18, further comprising:a second CIM-containing sol-gel layer comprising a second CIM and asecond polymer composite of one or more alkoxysilanes, a zirconiumalkoxide, and an organic acid; wherein the second CIM comprises: a Zn—Allayered double hydroxide (LDH) composition comprising nanoparticles ofZn—Al LDH, each nanoparticle of Zn—Al LDH having a size ranging fromabout 1 nm to about 1000 nm; and a second corrosion inhibitorintercalated in the nanoparticles of the Zn—Al LDH, the second corrosioninhibitor.
 20. The corrosion-resistant coated product of claim 19,wherein the second corrosion inhibitor comprises1-(3-aminopropyl)imidazole, 1H-1,2,3-triazole,4-methyl-4H-1,2,4-triazole-3-thiol, 1,2,4-triazole-3-carboxylic acid,3-amino-1,2,4-triazole-5-thiol, 4H-1,2,4-triazol-4-amine,3-mercapto-4-methyl-4H-1,2,4-triazole,5-phenyl-1H-1,2,4-triazole-3-thiol, 1-methyl-1H-tetrazole-5-thiol,1H-tetrazole-5-acetic acid, 4-methyl-1,3-thiazole-5-carboxylic acid,1,3,4-thiadiazole-2,5-dithiol, 1H-benzimidazole-2-carboxylic acid,1H-benzotriazole (BTA), 2-mercaptobenzothiazole (MBT),8-hydroxyquinoline, phytic acid, an organophosphonic acid, a vegetableoil, a vanadate, a molybdate, a tungstate, a phosphate, a manganate, apermanganate, an aluminate, or a combination thereof.